化简: 1 a - 1 - 1 a 2 + a ÷ a 2 - 1 a 2 + 2 a + 1
计算:sin600cos300+
.计算:-2+(π-1)0+tan60°-;
(2-3)+(2+)(2-);
计算: (1)+6-2;
计算. (1)(2) (3)(4)3x-( 2x-4) +(2x-1)